German fears were soon justified. The Swedish aeroplane cruiser Gotland was conducting firing exercises off Vinga. At 13.00 hours Lütjens reported to Marinegruppe Nord that the Gotland had been sighted. But what really mattered was that the Gotland had reported the observation of two battleships of Bismarck-class, and three destroyers. The erroneous identification of the Prinz Eugen is understandable, as the silhouettes of two ships differed little. At a distance, the Gotland followed the German squadron, until 15.45 hours, when the Germans set a northwesterly course.¹⁷⁸ However, the Gotland had not been the first to report the German squadron to the Swedes. Just before her report, a Swedish aircraft had reported that three destroyers, one cruiser and a larger warship presumed to be the Bismarck sailed on a northerly course 35 kilometres from Vinga.¹⁷⁹

Before long, it became apparent that Operation Rheinübung was no longer a secret. The question was what neutral Sweden would do with the information obtained? It was by no means certain that the knowledge about the two heavy German warships would be passed on. The Germans regarded Swedish neutrality as fairly benevolent and Admiral Carls, commander of Marinegruppe Nord, did not believe the information would leave Sweden.¹⁸⁰ But even if there were no intention to inform the British, there was always a risk that leaks would provide the British with information.

We do not know Lütjens’ opinion on the issue. From a military ship secrecy could be expected, but the civilians did not have such limitations. Perhaps the Gotland was regarded as a lesser risk than the small fishing-boats. On the other hand, the Swedish military of course had much better means of distributing the information rapidly. In any case, the British would need the information quickly if they were to prevent the German break-out, which was the critical consideration. Lütjens’ experiences from Operation Berlin suggested that it was very difficult to find his squadron once it had reached the expanses of the Atlantic. Thus, the Swedish observers need not be much of a problem.

While Lütjens’ squadron continued on its course towards the southern coast of Norway, another drama took place south of Cape Farewell, the southernmost point of Greenland. Here the British convoy HX126 from Nova Scotia was attacked by several submarines and suffered serious losses. Its worst day was 20 May, when no less than seven ships fell prey to the German U-boats. Of these, three fell victim to Herbert Wohlfahrt and U-556. He had already torpedoed the British Security and Cockaponset, when he found a straggler, the freighter Darlington Court.¹⁸¹ Wohlfahrt only had one torpedo left, but he decided to attack. The navigation officer objected and suggested that it might be better to save the remaining torpedo for a better target on the way home, but Wohlfahrt replied: ‘Better a sparrow today than a possible pigeon tomorrow.’¹⁸² He fired the last torpedo and the Darlington Court gradually capsized and sank in the Atlantic. A week later he was to bitterly regret this action.

On board Lütjens’ ships, the tension mounted. The time for the break-out came nearer and nearer. Had the British any inkling of the German actions? A German reconnaissance aircraft flew over Scapa Flow and this time weather was more favourable. The air crew reported it had seen one carrier, three battleships and four cruisers in the main base of the Home Fleet. Thus, Lütjens concluded that the main strength of the Home Fleet remained in port. Had these ships weighed anchor, it would have been a strong indication that the British had become aware of the German plans.¹⁸³

Towards the evening of 20 May the German squadron approached the south coast of Norway, not far from Kristiansand and as the sun set, the German lookouts could see land on the starboard side: magnificent scenery with the beautiful Norwegian coastline glowing beneath a red sky. Few seamen had the time to look at the view. The area was known to be dangerous, as it was patrolled by British submarines. The German ships zigzagged at 17 knots. During the night, the hydrophone operators on board the Prinz Eugen registered propeller noise that might originate from a submarine. Otherwise, the night passed uneventfully.

On the morning of 21 May, the B-Dienst on the Prinz Eugen intercepted a British wireless signal instructing an air unit to search for two battleships and three destroyers on a northerly course.¹⁸⁴ Except for the mistaken identification of the Prinz Eugen, this was a correct description of Lütjens’ squadron.

Soon thereafter another ominous observation was made. ‘Shortly after 07.00,’ Müllenheim-Rechberg remembered, ‘four aircraft came into view—mere specks against the sun. Were they British or our own? So quickly did they vanish that we wondered if we had imagined them.’

The aeroplanes were so distant that their type or nationality could not be determined, but nevertheless the observation was troublesome. The B-Dienst was of the opinion that the aircraft did not transmit any radio signal, but when the German squadron approached the Korsfjord south of Bergen, there were strong indications that it had been discovered.¹⁸⁵

When Lütjens’ ships weighed anchor in Gdynia, the British had their eyes rivetted on the events in the Mediterranean and on the submarine warfare in the Atlantic. A few weeks earlier, German army units had pushed an Allied expeditionary force off mainland Greece, forcing the British to yet another seaborne evacuation. The Commonwealth troops were shipped to Egypt and Crete and Churchill decided that Crete should be defended. Crete’s geographical position was almost as strategically important as Malta and there still remained time to strengthen her defences.

In North Africa, Rommel had recaptured the areas taken by General Richard O’Connor during his offensive against the Italians in December 1940. Three days before Lütjens’ squadron sailed from Gdynia, British forces in North Africa, commanded by General Archibald Wavell, launched Operation Brevity. The offensive was stopped dead in its tracks by Rommel. No useful results were produced by the British attack and the overall situation in the desert remained precarious. In addition to the problems in Africa, the British had strong indications that the Germans intended to attack the Soviet Union.

To all these worries, the situation on the Atlantic was added, where the German submarines continued their ravaging and further attacks from German cruisers and battleships were expected. No German surface ships had been in action in the Atlantic since the end of March, but evidently the Bismarck and Prinz Eugen were combat-ready by mid-May. On the other hand, available British intelligence suggested that the Scharnhorst and Gneisenau were not ready for action yet, as they probably were not fully repaired. For the Home Fleet, the major threat came from the Bismarck, the Prinz Eugen and possibly from the Tirpitz.

Admiral Tovey strived to keep as good a surveillance as possible over the most critical areas, without taxing the endurance of his ships and men. In particular, he had to be foresighted about the Denmark Strait, as it lay a considerable distance from the British bases, making it difficult to send reinforcements to the area without ample fore-warning. For the time being, the first cruiser division, comprising the heavy cruisers Norfolk and Suffolk commanded by Rear-Admiral Frederick Wake-Walker was guarding the Denmark Strait.